Research On The Statistics And Network Model Of Rock Bridges On Rock Mass Structural Plane Based On Digital Measurement Technology

The study on the developmental characteristics of the surrounding rock mass structure of the candidate site in the underground laboratory is particularly important.Based on the digital measurement technology,taking the outcrop as an example,the multi-view photogrammetry technology is used to perform the three-dimensional reconstruction of the outcrop based on the Sf M algorithm,and the three-dimensional digital model of the outcrop surface is obtained.In this context,Under this background,the main work and conclusions of this paper are as follows:(1)The method of extraction of structural attitudes from 3D digital model is studied.Meshlab was used to sampling the linear discontinuities appearing on the 3D digital model as trace,and the linear geometry method was used to calculate the structural attitudes(orientation,trace length)of the linear discontinuities.Meshlab was used to sampling the planer discontinuities appearing on the three-dimensional digital model as the individual expose surfaces,and the principal component analysis method is used to calculate the normal vector perpendicular to the surface of the planer discontinuities,and the orientation of the discontinuities is calculated.The trace length of the discontinuities is estimated according to the vertex set of the planar discontinuities.virtual scanline was placed on the three-dimensional digital model to calculate the average space of discontinuities and line density of the discontinuities.The program was written with Python programming language,the structural attitudes of multiple discontinuities on the outcrop are obtained,and the results are compared with the surveys undertaken using traditional compass reading,which proves that the method is accurate,efficient and reliable.(2)According to the orientation of discontinuities,the fast fuzzy clustering method is used to group the dominant discontinuities.Meshlab was used to estimate the mean length of the trace and the density of discontinuities on the threedimensional digital model by place the topographical of the circular window.The virtual scanline was arranged on the three-dimensional digital model to estimate the discontinuities plane spacing.The method was applied on two rock outcrops YZ1 and YZ2.The results show that the method provides the ability to sample the outcrop with circular window and the scanline on the computer.(3)A three-dimensional discrete fracture network model of two outcrops of rock mass is established.The steps of generating the three-dimensional discrete fracture network model was described.The Steps of generating the three-dimensional discrete fracture network model was based on the previous research.The program is written in the programming language Python.The three-dimensional Mesh model data and the extensible markup language file obtained after sampling are imported into the grouping interval.A three-dimensional network model can be generated.(4)Arranging three-dimensional circular windows on the three-dimensional digital model,using two methods to estimate the parameters R21 and R10 of the coplanar rock bridge and the non-coplanar rock bridge on the rock outcrop,respectively,and the differential evolution algorithm was used.The influence of rock bridge parameters on the diameter parameters of the disc optimizes the three-dimensional structural plane digital model,and the result show a good correlation.